ATLANTA --- The nation's busiest airport dueled with gun rights advocates Tuesday over whether a new Georgia law allows visitors to carry firearms at Hartsfield-Jackson Atlanta International Airport.

City officials in charge of the airport declared it a "gun-free zone" when a law allowing people to carry guns on public transit and other places took effect Tuesday. Gun rights supporters, including a state legislator who helped pass the law, quickly filed a lawsuit in federal court challenging the designation.

"My message is simple: Leave your firearms at home," airport general manager Ben DeCosta told reporters at a news conference.

Atlanta officials said anyone carrying a gun at the airport could be arrested and charged with a misdemeanor.

The new law allows people with a concealed-weapons permit to carry guns into restaurants, state parks and on public transportation.

John Monroe, an attorney for the gun rights backers who filed the lawsuit, argued the Atlanta airport qualifies as public transportation. There are also restaurants in the terminal, which Mr. Monroe said should be accessible to gun-toting visitors under the law.

Rep. Tim Bearden, a Republican from Villa Rica and a former police officer, is a plaintiff in the lawsuit. He sponsored the law.

He had told a newspaper he would carry a concealed weapon to the airport Tuesday when he picked up his family. But he told The Associated Press by telephone Tuesday morning, "There will be no reason for any confrontation at the airport."

The gun group argues that weapons should be allowed in the terminal up to the point where passengers pass through security to board their flights. The parking lot is off limits under the state law, but it allows travelers to carry a gun on MARTA trains and buses, which run directly to the airport.

Atlanta Mayor Shirley Franklin said residents can't bring guns into the terminal and argued that airports remain attractive targets for terrorism. She said she will lobby Congress to withhold federal funds from facilities that allow firearms on their premises.